This invention relates generally to resolution enhancement circuits and, more particularly, to circuits for multiplying the resolution of output signals from speed and displacement sensors.
Traditionally, increased resolution with speed or displacement sensors has been achieved by mechanical multiplication. For example, if magnetic poles and digital Hall-effect sensors are used to produce data points, additional magnetic poles or sensors may be added between initial magnetic poles or sensors to achieve closer spacing between data points. Such increased resolution is limited by space requirements for the additional poles and sensors and by the associated costs of the additional components.
In addition to problems related to space requirements and cost, inherent drifting of the switch points of the digital sensors results in inaccuracy of the sensing system, particularly since all the sensors may not drift the same way with respect to time, temperature, and other conditions. Variations in air gap, sensor gain, signal amplitude, and bias of the magnetic field during operation may also reduce the accuracy of the sensing system.
Another known method to increase resolution with speed or displacement sensors is to compare signals from two or more sensors to produce intermediate data points electronically. For example, when two sensors are positioned to produce signals that are 90 degrees out of phase, the signals may be combined in various percentages to provide additional data points by interpolation. However, the intermediate points will not be placed accurately if the signals of the two sensors do not drift the same way.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.